platform.system_alias() documentation:

   Returns ``(system, release, version)`` aliased to common marketing names used
   for some systems.  It also does some reordering of the information in some cases
   where it would otherwise cause confusion.

IMHO "macOS" and macOS release are more appropriate than darwin and darwin release for platform.system_alias().

I propose to make a similar change in system_alias() than the platform.mac_ver() change made in bpo-35344.

> than the platform.mac_ver() change made in bpo-35344

Oops, this issue changed platform.platform() (not platform.mac_ver()).

The patch does not use the version information passed in to calculate the marketing version. That's a problem when passing in low-level information from a system running a different version of macOS (for example passing in the low-level version information from a macOS 10.8 system while the script is running on a macOS 10.14 system).

> The patch does not use the version information passed in to calculate the marketing version. That's a problem when passing in low-level information from a system running a different version of macOS (for example passing in the low-level version information from a macOS 10.8 system while the script is running on a macOS 10.14 system).

Right. The function has a weird API. Maybe the function shouldn't be fixed in this case. If we don't fix it, I would like to at least document why the function doesn't replace Darwin with macOS.

Ronald Oussoren:
> The patch does not use the version information passed in to calculate the marketing version. That's a problem when passing in low-level information from a system running a different version of macOS (for example passing in the low-level version information from a macOS 10.8 system while the script is running on a macOS 10.14 system).

I abandonned my PR 11187 and I wrote PR 11207 to add a comment explaining why Darwin is not replaced with macOS.

Well, use platform.platform() or platform.mac_ver() to get the macOS version ;-)

New changeset 60875db2f67815d7d181c552bfac59e8c97619e3 by Victor Stinner in branch 'master':
bpo-35516: platform.system_alias() don't replace Darwin (GH-11207)
https://github.com/python/cpython/commit/60875db2f67815d7d181c552bfac59e8c97619e3